The present invention relates to a dustproof mechanism for maintaining the detecting accuracy of the detecting means for detecting substances to be detected.
In conventional mechanisms, many detecting means for detecting a number, shape, length, widths of substances to be detected (e.g., tablets, metal parts such as bolts and nuts, which are produced in a large amount at one process, semiconductor elements such as emitting diodes, and plastic parts) has been proposed.
For example, in the case of the detecting means for counting a number of tables which are substances to be detected, the detecting means is configured that tables stored in a hopper for counting are gradually transferred from an outlet of the hopper, and a light detecting sensor, which is a detecting means, is provided at a position of the outlet. The transferred tablets are counted by passing the tablets through a detecting light path placed between a light transmitting portion and a light receiving portion of the light detecting sensor.
In some cases, the detecting means utilizes a light detecting sensor as a so-called image sensor, and a construction of light permeating type that the light transmitting portion and the light receiving portion are placed opposite each other and a construction of reflecting type that the light transmitting portion and the light receiving portion are placed on the same side have been known.
Also, an apparatus for counting a large number of substances to be detected at a high speed in a precision manner in which the substances to be detected are aligned by a centrifugal force or vibration possesses a detecting means at the position where the substances to be detected are transferred. At the present situation, the light detecting sensor has been utilized as the detecting means for such an apparatus.
However, the conventional detecting means has the following problems:
(1) In the detecting means, during the course of passing the substances to be detected through the detecting position, dusts or proof inherent to the substance to be detected themselves, caused by the rusting the substances to be detected with each other when they are stored or arranged, or rusting the substances to be detected by contact with the container to be stored, such as powders in the case of foods or tablets, plastic powders in the case of plastic products, metal dusts in the case of metal parts, or vaporized oils caused from the oils adhered onto the metal parts, are transferred to the detecting position together with the substances to be detected, and the detecting position is filled with such dusts etc. Consequently, the powders or vaporized oils are adhered to the light transmitting portion, light receiving portion or reflecting mirror of the detecting means to decrease the detecting accuracy of the detecting means.
(2) Since the detecting accuracy of the detecting means is decreased when the detecting means is stained by adhering powders etc. onto the detecting portion (light transmitting portion, light receiving portion and reflecting mirror), cleaning must be carried out after several operations of the detecting means. For this reason, the detecting operation such as counting must be stopped to constantly carry out maintenance within a short running.
(3) Particularly, in the case of the detecting means for use in high performance counting apparatus, since a larger amount of dusts etc. occurs because the apparatus counts a large amount of the substances to be detected at a high speed, the decrease in the accuracy is remarkable due to the adhesion of powders onto the light transmitting portion, light receiving portion or the reflecting mirror. The adhered powders, etc. onto the detecting portion must be cleaned every constant period of time.
(4) In some detecting means, the side walls are formed on the detecting position. When the powders etc. are adhered onto the side walls, error information is sometimes transferred to the light receiving portion. Consequently, the construction of the detecting position must be considered in order to enhance the detecting accuracy.
The present invention has been proposed in order to solve the problems associated with the prior art. An object of the present invention is to provide a dustproof mechanism (1) which can minimize the adhesion of powders onto the detecting portion of the detecting means, (2) which can minimize the cleaning of the detecting portion, (3) which can be installed to the resent existing apparatus, (4) which has a simple structure that only adequate information can be transferred to the detecting position to the light receiving portion, and (5) which can also minimize the adhesion of powders even in the case of high performance counting apparatus.
A dustproof mechanism of the present invention is for the purpose of dust proofing a detecting means comprising a detecting position, through which substances to be detected are passed at a prescribed position of a detecting optical path, which is formed on one side of the detecting position. In the dustproof mechanism of the present invention, at least two air chambers being provided between the detecting portion and the detecting position in a manner that these air chambers are perforated through the optical path to make open holes.
In a preferred embodiment of the present invention the dustproof mechanism also provides detecting portions at opposite sides of the detecting position.
In another preferred embodiment of the present invention, the detecting portion may be composed of a light emitting portion and a light receiving portion, or may be composed of a light emitting portion, a light receiving portion and a reflecting mirror.
In a preferred embodiment of the dustproof mechanism, a gas supply means is connected to the air chamber provided at the side far from the position of the detecting position, so that a gas is supplied from the air chamber connected to the gas supply means toward the side of the detecting position.
In another preferred embodiment of the dustproof mechanism, the air chambers are formed so that the capacity becomes gradually smaller toward the position far from the detecting position.
In still another preferred embodiment of the dustproof mechanism, the two or more air chambers are provided by dividing each of the air chambers by the dividing plate in a manner of making open holes on the detecting optical path.
Also, it is possible for the dustproof mechanism according to the present invention to provide a sidewall formed along the optical path in such a manner that a slant angle is provided which does not reflect a light from the light emitting part on the light reviving part.